During the post-harvest storage of plant produce, such as fruits, vegetables and flowers, it is observed that a natural ripening agent (ethylene gas) is released into the surrounding or into the storage containers leading to a change in color, texture, aroma, and nutritional quality of the plant produce. It is also observed that excessive or uncontrolled levels of ethylene gas may result in premature ripening of fruits and vegetables, the fading and wilting of cut flowers, loss of green color, increase in the bitterness of vegetables and the like. Therefore, it is desirable to control the ethylene gas concentration in order to prolong the shelf-life of plant produce. This can be achieved either by reducing the formation of ethylene gas by the plant produce or by reducing the concentration of ethylene gas already formed.
Conventionally, the formation of ethylene gas is reduced either by storing the plant produce in a cold storage at a temperature of −1 to +12° C. and at a relative atmospheric moisture of 80 to 90% or by storing it in a controlled atmosphere at a temperature range of 0 to 5° C. with approximately 3% of oxygen and 0 to 5% of carbon dioxide. However, the above stated storage conditions negatively influence the taste of certain plant produce due to low oxygen content and high carbon dioxide content.
Further, known methods disclose the use of oxidizing agents to convert ethylene gas into carbon dioxide and water. The oxidizing agent includes potassium bromate supported on activated charcoal; silver, alumina, copper and aluminum chloride exchanged zeolite A; palladium chloride supported on carbon; sodium chloride saturated on silica and zeolites; sodium and potassium permanganate impregnated on various carriers like activated carbon, alumina, zeolites and diatomaceous earth. Among these potassium permanganate is observed to be the most effective for converting ethylene into carbon dioxide and water. However, leaching of potassium permanganate at a high humidity of 80 to 90% limits its use.
Packaging containers prepared by using fibers containing silver and copper exchanged hydrophilic zeolites like Zeolite A and X impart good antimicrobial properties but have a limited capacity to remove ethylene.
Therefore, there is a need to envisage a fiber suitable for packaging and capable of reducing the ethylene gas evolved during the ripening process of the stored plant produce.